An Idaho man has been arrested in connection with the killing of a Marin County mother that shocked the quiet community in the 1970s. Michael Eugene Mullen, 75, is in custody and awaiting extradition to California. On the morning of Nov. 15, 1973, Swedish business executive Gunnar Fischer left for work in San Francisco. It was a busy time for the young Fischer family: Gunnar and his 31-year-old wife Nina “Nadine” Fischer were packing up their home on Point San Pedro Road in San Rafael for the big move back to Sweden, where they both grew up. Along with their…